Ransomware written in Go.
rule win_jcry_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2020-10-14" version = "1" description = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.5.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.jcry" malpedia_rule_date = "20201014" malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9" malpedia_version = "20201014" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" /* DISCLAIMER * The strings used in this rule have been automatically selected from the * disassembly of memory dumps and unpacked files, using YARA-Signator. * The code and documentation is published here: * https://github.com/fxb-cocacoding/yara-signator * As Malpedia is used as data source, please note that for a given * number of families, only single samples are documented. * This likely impacts the degree of generalization these rules will offer. * Take the described generation method also into consideration when you * apply the rules in your use cases and assign them confidence levels. */ strings: $sequence_0 = { 8b442424 8907 8d0560434f00 890424 c74424040d000000 c744240800000000 } // n = 6, score = 100 // 8b442424 | mov eax, dword ptr [esp + 0x24] // 8907 | mov dword ptr [edi], eax // 8d0560434f00 | lea eax, [0x4f4360] // 890424 | mov dword ptr [esp], eax // c74424040d000000 | mov dword ptr [esp + 4], 0xd // c744240800000000 | mov dword ptr [esp + 8], 0 $sequence_1 = { c744240400000000 e8???????? 8b44240c 8b4c2408 8d1500a44f00 891424 894c2404 } // n = 7, score = 100 // c744240400000000 | mov dword ptr [esp + 4], 0 // e8???????? | // 8b44240c | mov eax, dword ptr [esp + 0xc] // 8b4c2408 | mov ecx, dword ptr [esp + 8] // 8d1500a44f00 | lea edx, [0x4fa400] // 891424 | mov dword ptr [esp], edx // 894c2404 | mov dword ptr [esp + 4], ecx $sequence_2 = { 890c24 8b542420 89542404 8d1de6fd5000 895c2408 c744240c0a000000 e8???????? } // n = 7, score = 100 // 890c24 | mov dword ptr [esp], ecx // 8b542420 | mov edx, dword ptr [esp + 0x20] // 89542404 | mov dword ptr [esp + 4], edx // 8d1de6fd5000 | lea ebx, [0x50fde6] // 895c2408 | mov dword ptr [esp + 8], ebx // c744240c0a000000 | mov dword ptr [esp + 0xc], 0xa // e8???????? | $sequence_3 = { ebdd 89442434 8d0540d34e00 890424 895c2404 89542408 896c240c } // n = 7, score = 100 // ebdd | jmp 0xffffffdf // 89442434 | mov dword ptr [esp + 0x34], eax // 8d0540d34e00 | lea eax, [0x4ed340] // 890424 | mov dword ptr [esp], eax // 895c2404 | mov dword ptr [esp + 4], ebx // 89542408 | mov dword ptr [esp + 8], edx // 896c240c | mov dword ptr [esp + 0xc], ebp $sequence_4 = { 0f0b e8???????? 0f0b 8d05bc415100 890424 c74424041a000000 e8???????? } // n = 7, score = 100 // 0f0b | ud2 // e8???????? | // 0f0b | ud2 // 8d05bc415100 | lea eax, [0x5141bc] // 890424 | mov dword ptr [esp], eax // c74424041a000000 | mov dword ptr [esp + 4], 0x1a // e8???????? | $sequence_5 = { 8b4c2448 894c242c 890424 c744240404000000 8b442434 89442408 8b442430 } // n = 7, score = 100 // 8b4c2448 | mov ecx, dword ptr [esp + 0x48] // 894c242c | mov dword ptr [esp + 0x2c], ecx // 890424 | mov dword ptr [esp], eax // c744240404000000 | mov dword ptr [esp + 4], 4 // 8b442434 | mov eax, dword ptr [esp + 0x34] // 89442408 | mov dword ptr [esp + 8], eax // 8b442430 | mov eax, dword ptr [esp + 0x30] $sequence_6 = { 897c2434 8d44f108 8b00 89442430 e8???????? 8d0527845100 890424 } // n = 7, score = 100 // 897c2434 | mov dword ptr [esp + 0x34], edi // 8d44f108 | lea eax, [ecx + esi*8 + 8] // 8b00 | mov eax, dword ptr [eax] // 89442430 | mov dword ptr [esp + 0x30], eax // e8???????? | // 8d0527845100 | lea eax, [0x518427] // 890424 | mov dword ptr [esp], eax $sequence_7 = { 8b442468 83f80a 0f85f8030000 8d0540425e00 890424 e8???????? 8d0548425e00 } // n = 7, score = 100 // 8b442468 | mov eax, dword ptr [esp + 0x68] // 83f80a | cmp eax, 0xa // 0f85f8030000 | jne 0x3fe // 8d0540425e00 | lea eax, [0x5e4240] // 890424 | mov dword ptr [esp], eax // e8???????? | // 8d0548425e00 | lea eax, [0x5e4248] $sequence_8 = { 8b6c2430 eb93 8d0da0275000 890c24 8b6c2438 896c2404 } // n = 6, score = 100 // 8b6c2430 | mov ebp, dword ptr [esp + 0x30] // eb93 | jmp 0xffffff95 // 8d0da0275000 | lea ecx, [0x5027a0] // 890c24 | mov dword ptr [esp], ecx // 8b6c2438 | mov ebp, dword ptr [esp + 0x38] // 896c2404 | mov dword ptr [esp + 4], ebp $sequence_9 = { 8b4c243c 89c2 89c8 89d1 e9???????? 8d05aef65000 b907000000 } // n = 7, score = 100 // 8b4c243c | mov ecx, dword ptr [esp + 0x3c] // 89c2 | mov edx, eax // 89c8 | mov eax, ecx // 89d1 | mov ecx, edx // e9???????? | // 8d05aef65000 | lea eax, [0x50f6ae] // b907000000 | mov ecx, 7 condition: 7 of them and filesize < 4137984 }
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